Caption: Hydroelectric power station. This small scale generating station (HEP) utilizes a waterfall to turn turbines, which generate electricity. HEP stations are frequently used during periods of high electricity demand. This is because they can easily control how much electricity they produce, by opening or closing floodgates in the feed pipe. This station supplies a small local community, and any surplus electricity is sold to the National Grid. Photographed near Loch Beoraid, Scotland.